Class UUID

A class that represents an immutable universally unique identifier (UUID).
A UUID represents a 128-bit value.

There exist different variants of these global identifiers. The methods
of this class are for manipulating the Leach-Salz variant, although the
constructors allow the creation of any variant of UUID (described below).

The layout of a variant 2 (Leach-Salz) UUID is as follows:
The most significant long consists of the following unsigned fields:

The variant field contains a value which identifies the layout of the
UUID. The bit layout described above is valid only for a UUID with a variant value of 2, which indicates the Leach-Salz variant.

The version field holds a value that describes the type of this UUID. There are four different basic types of UUIDs: time-based, DCE
security, name-based, and randomly generated UUIDs. These types have a
version value of 1, 2, 3 and 4, respectively.

timestamp

public long timestamp()

The timestamp value associated with this UUID.

The 60 bit timestamp value is constructed from the time_low,
time_mid, and time_hi fields of this UUID. The resulting
timestamp is measured in 100-nanosecond units since midnight,
October 15, 1582 UTC.

The timestamp value is only meaningful in a time-based UUID, which
has version type 1. If this UUID is not a time-based UUID then
this method throws UnsupportedOperationException.

equals

Compares this object to the specified object. The result is true if and only if the argument is not null, is a UUID
object, has the same variant, and contains the same value, bit for bit,
as this UUID.